The BACnet communications protocol can be implemented to control and monitor facility automation and control equipment. The BACnet protocol includes network and application layers that can be implemented over several different data layer and physical layer protocols, as that term us used in the Open Systems Interconnection (“OSI”) model (ISO/IEC 7498-1), such protocols including Ethernet protocol (IEEE 802.2), ARCNET and EIA-485. The EIA-485 physical layer is a commonly used physical layer standard in facility control systems. Since EIA-485 is a physical layer standard, it does not regulate access to the transmission medium. BACnet defines a Master-Slave/Token-Passing (“MS/TP”) protocol to provide a data link layer function to complement the EIA-485 physical layer standard.
Building automation and control networks, such as those complying with the BACnet communications protocol, can include multiple automation and control devices. For proper operation of the building automation and control network and the devices connected to such a network, correct addresses can be required for each device on the network. For example, each MS/TP device installed in a BACnet building control system requires two addresses to be properly configured, and thus before the device can communicate over the BACnet network: the MAC address and the device object identifier (“device object ID”). The MAC address can be unique for each device on the local MS/TP network or bus, while the device object ID can be unique for each device over the entire BACnet automation and control network. Duplicate addresses can impair not only the function of the devices with the duplicate addresses, but the entire network. Such address conflicts can be time consuming to identify and fix. It is therefore desirable to select valid addressing information for a particular device, in particular upon installation of the device on the network.